Associations between pericytes and capillary endothelium in the eel rete mirabile.

Morphometric analysis of electron micrographs of the eel rete mirabile revealed that pericytes occupied nearly one-third of the cellular volume of this organ with over 75% of the pericyte volume associated with arterially derived capillaries. These pericytes were highly arborized, extending processes which encircled the capillaries and covering, on average, more than 85% the ablumenal surface of arterially derived capillaries. Pericytes and endothelial cells interacted in a manner suggesting that pericyte activity modulates both capillary blood flow and permeability.